• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.3
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• pp.289-295
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• 2004

Pressure tubes are major component of nuclear reactor, but only selected samples are periodically examined due to numerous numbers of tubes. Current in-service inspection result show there is high probability of flaw existence at uninspected pressure tube. Probabilistic analysis is applied in this study for the integrity assessment of uninspected pressure tube. All the current integrity evaluations procedures are based on conventional deterministic approaches. So it is expected that the results obtained are too conservative to perform a rational evaluation of lifetime. More realistic failure criteria, based on FAD are also proposed for the probabilistic analysis. As a result of this study failure probabilities for various conditions are calculated, and examined application of FAD and LBB concept.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.385-386
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• 2006

A brake disk in railway vehicle is safety part. Requirements not only in performance but also in comfort, serviceability and working lifetime are high and rising. In this study, we carried out fatigue test and thermal stress analysis. To determine a pressure distribution, contact pressure analysis precede thermal stress analysis. Especially, characteristics of the brake disk were analyzed in considering intial velocity, and thickness of a frictional plate. Form the comparing the results of experiment and FEM analysis, fatigue characteristic and fatigue life assessment ok a brake disk of railway vehicle were performed.

• Journal of Environmental Science International
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• v.22 no.12
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• pp.1579-1587
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• 2013

This study was performed to evaluate the asbestos exposure levels and to calculate excess lifetime cancer risk (ELCR) for the risk assessment of the asbestos fibers released from asbestos-cement slate roofing (ASR) building. Total number of ASR buildings was into 21,267 in Busan, and 82.03 percent of the buildings was residential houses, and 43.61 percent of the buildings was constructed in 1970s. For this study, ten buildings were selected randomly among the ASR buildings. The range of airborne asbestos concentration in the selected ten ASR buildings was from 0.0016 to 0.0067 f/mL, and the concentration around no-admitted ASR buildings was higher than that around admitted buildings. The ELCR based on US EPA IRIS (integrated risk information system) model is within 3.5E-05 ~ 1.5E-04 levels, and the ELCR of no-admitted ASR buildings was higher than 1.0E-04 (one person per million) level that is considered a more aggressive approach to mitigate risk. These results indicate that the cancer risk from ASR buildings is higher than other buildings, and systematic public management is required for control of no-admitted ASR buildings within near future.

• Safety and Health at Work
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• v.7 no.3
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• pp.251-255
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• 2016

Background: Building demolition can lead to emission of dust into the environment. Exposure to silica dust may be considered as an important hazard in these sites. The objectives of this research were to determine the amount of workers' exposure to crystalline silica dust and assess the relative risk of silicosis and the excess lifetime risk of mortality from lung cancer in demolition workers. Methods: Four sites in the Tehran megacity region were selected. Silica dust was collected using the National Institute for Occupational Safety and Health method 7601 and determined spectrophotometrically. The Mannetje et al and Rice et al models were chosen to examine the rate of silicosis-related mortality and the excess lifetime risk of mortality from lung cancer, respectively. Results: The amount of demolition workers' exposure was in the range of $0.085-0.185mg/m^3$. The range of relative risk of silicosis related mortality was increased from 1 in the workers with the lowest exposure level to 22.64/1,000 in the employees with high exposure level. The range of the excess lifetime risk of mortality from lung cancer was in the range of 32-60/1,000 exposed workers. Conclusion: Geometric and arithmetic mean of exposure was higher than threshold limit value for silica dust in all demolition sites. The risk of silicosis mortality for many demolition workers was higher than 1/1,000 (unacceptable level of risk). Estimating the lifetime lung cancer mortality showed a higher risk of mortality from lung cancer in building demolition workers.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.270-275
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• 2019

Mica capacitor is being adopted for high voltage firing unit of guided weapon system because of its superior impact enduring property relative to ceramic capacitor. Reliability of localized mica high voltage capacitors was verified through environmental test like terminal strength test, humidity test, thermal shock test and accelerated life test for application to high voltage firing unit. Failure mode of mica capacitor is a decrease of insulation resistance and its final dielectric breakdown. Main constants of accelerated life model were derived experimentally and voltage constant and activation energy were 5.28 and 0.805 eV respectively. Lifetime of mica capacitor at normal use condition was calculated to be 38.5 years by acceleration factor, 496, and lifetime at accelerated condition and this long lifetime confirmed that mica high voltage capacitor could be applied for firing unit.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6A
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• pp.965-976
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• 2006

A realistic lifetime seismic-reliability based approach is unavoidable to perform Life-Cycle Cost (LCC)-effective optimum design, maintenance, and retrofitting of structures against seismic risk. So far, though a number of researchers have proposed the LCC-based seismic design and retrofitting methodologies, most researchers have only focused on the methodological point. Accordingly, in most works, they have not been quantitatively considered critical factors such as the effects of seismic retrofit, maintenance, and environmental stressors on lifetime seismic reliability assessment of deteriorating structures. Thus, in this study, a systemic lifetime seismic reliability analysis methodology is proposed and a program HPYER-DRAIN2DX-DS is developed to perform the desired lifetime seismic reliability analysis. To demonstrate the applicability of the program, it is applied to an example bridge with or without seismic retrofit and maintenance strategies. From the numerical investigation, it may be positively stated that HYPER-DRAIN2DX-DS can be utilized as a useful numerical tool for LCC-effective optimum seismic design, maintenance, and retrofitting of bridges.

• Journal of Applied Reliability
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• v.18 no.3
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• pp.260-270
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• 2018

Purpose: The purpose of this study is to evaluate the life of the capsule, which is a core part of the heat storage cooling system. This paper will develop a life test mode that can reproduce environment conditions through the analysis of capsule shrinkage and expansion characteristics. Methods: In order to determine the life test mode of the capsule, this paper analyzed the case of field failures and analyzed the deformation characteristics according to the pressure fluctuation of the capsule. The method to find out whether the field failure and deformation analysis results are consistent is the testing with the construction of the repetition pressure test equipment and the thermal cycle test to reproduce the freezing and thawing characteristics. Results: In this study, failure mode analysis and analysis of freezing and thawing characteristics regarding to the capsule positions were completed. Based on this test & analysis results, this paper have been able to determine the main parameters for determining the life test mode, the freezing and thawing time. Conclusion: Determining the lifetime mode of the capsule can be used to improve the life and performance of the thermal storage system.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.1
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• pp.303-306
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• 2015

Purpose: This study was conducted to determine risk of developing of breast cancer among Turkish women. Materials and Methods: Using a descriptive and cross-sectional approach, data were collected from 231 women. Breast cancer risk was calculated using the National Cancer Institute's on-line verson of called as the Breast Cancer Risk Assessment Tool or the Gail Risk Assesment Tool. Results: The average age of women was $45.0{\pm}8.06$ years. It was revealed that 6.1% of participants reported having first degree relatives who had had breast cancer, with only four women having more than one first-degree relative affected (1.7%). The mean five-year breast cancer risk for all women was $0.88{\pm}0.91%$, and 7.4% of women had a five-year breast cancer risk >1.66% in this study. Mean lifetime breast cancer risk up to age 90 years was $9.3{\pm}5.2%$. Conclusions: The breast cancer risk assessment tool can help in the clinical management of patient seeking advice concerning screening and prevention. Healthcare providers in Turkey can use this approach to estimate an individual's probability of developing breast cancer.

• Journal of the Korean Society of Safety
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• v.14 no.2
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• pp.103-108
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• 1999

This study focused on risk assessment for inhalation of airborne volatile organic compounds (VOCs) in Ulsan industrial complex area. For non-carcinogenic risk, even the highest hazard index of toluene was estimated to be $4.8\times10^{-2}$, which was much lower than 1. The total hazard index of VOCs was estimated to be $5.8\times10^{-2}$. However, lifetime average cancer risk from the inhalation of airborne VOCs was estimated to be about $1.1\times10^{-3}/$, which was much higher than a risk standard of $10^{-5}$. The risk of $4.4\times10^{-5}$. came from benzene, the only human carcinogen among VOCs, while that of $1.05\times10^{-3}$ from probable human carcinogens including 1,3-butadiene and 1,2-dichloroethane. About 70% and 20% of total VOC cancer risk was due to the inhalation of 1,3-butadiene and 1,2-dichloroethane, respectively. Therefore, proper risk management of these 3 VOCs was required for the protection of health from cancer burden in Ulsan industrial complex area.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.160-163
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• 2003

This paper represent a test method for the reliability assessment on the indoor vacuum circuit breakers used in the distribution system by an accelerated life test. In order to guarantee the lifetime in service of the vacuum circuit breaker, additional test methods are suggested. Multiple closing-opening operation test under no load condition as a mechanical endurance test and a check of the quality in the vacuum interrupter are adopted to assure the long-term reliability of the vacuum circuit breaker.